In U.S. Pat. No. 4,507,913 which is incorporated herein by reference, and in commonly owned U.S. Pat. Nos. 4,713,931 and 4,719,744, methods and apparatus are provided for efficiently and effectively producing yarn having properties approaching those of ring spun yarn, but at much greater speeds. The basic technique disclosed in said patents is known as "vacuum spinning", and it has a number of advantages compared to conventional techniques, as described in the above mentioned commonly owned patents. Improved vacuum spinning nozzle designs are disclosed in commonly owned U.S. Pat. No. 4,635,435.
The apparatus and method according to the present invention have substantially all of the same advantages described above with respect to vacuum spinning in general. In accordance with the present invention, a unique vacuum spinning nozzle is provided which has even further advantages.
In earlier vacuum spinning nozzle designs, one particularly satisfactory arrangement incorporates four orifice holes which radially communicate with the nozzle main passageway and through which an outward flow of air is created to draw some of the fibers up into the interior of the orifices momentarily, before they are wrapped about the remaining core fibers as the yarn continues its forward motion.
In one exemplary embodiment of the present invention, a vacuum spinning nozzle assembly is provided which comprises separable male and female cone sections axially aligned and slidably received within a peripheral sleeve. The composite male and female cone sections are formed with a longitudinally extending through passageway which includes a tapered inlet in the female cone section and an axially aligned and relatively straight portion extending through the male cone section. A radially outwardly extending, continuous conical slot is defined by facing, tapered surfaces of the female and male cone sections, the width dimension of which slot may be altered by relative axial movement of the male and/or female cone sections.
In use, a sliver is fed linearly into the tapered entry passageway of the female cone section of the nozzle assembly, and passed into the straight passageway portion of the male cone section. As the sliver fibers pass the radially outwardly directed slot, an applied or induced vacuum causes some surface fibers of the sliver to be drawn into the slot. As the fibers continue passage through the nozzle assembly, these displaced surface fibers will be pulled back from the slot and wrapped about the remaining core fibers as the nozzle assembly rotates about its longitudinal axis, which coincides with the direction of linear movement of the fibers.
It has been found that the ability to change the width dimension of the conical slot has beneficial effects in the production of yarns of different texture. For example, a relatively smaller slot provides better results for finer yarns whereas a relatively larger slot provides better results for coarser yarns.
Thus, in a related aspect, the present invention relates to methods of forming yarn by vacuum spinning wherein the conical slot dimension is altered in accordance with the desired yarn count.
Another advantage accrues by reason of the fact that a wider slot does not clog with fiber extractions such as vegetable matter, dirt, etc. as sometimes happens with the known multiple orifice arrangement.
The presently disclosed nozzle configuration also produces a yarn with a somewhat smoother surface, with less fiber bundles, while yarn strength is substantially equal to yarn produced with the conventional four orifice nozzle arrangement. It is therefore the primary object of the present invention to provide effective refinements and modifications of methods and apparatus for vacuum spinning of yarn. This and other objects of the invention will become apparent from the detailed description which follows .